1. Field of the Invention
The present invention concerns an apparatus for tightening, setting, tensioning or clamping of a cam shaft drive, which has two cam shafts connected with each other by an endless drive, preferably a chain, with two tensioning shoes, which engage along an inner side of each strand of the endless drive and which are fastened respectively to a piston means, of which at least one piston is engageable by hydraulic medium for tensioning of the endless drive of the cam shafts.
2. Description of the Prior Art
With such a known apparatus, at least one piston is engaged with hydraulic medium applied thereto, whereby the tensioning shoes are engaged against the two strands of the endless drive and thereby tensioning the endless drive. Via the arrangement of the cam shafts, accelerations and delays result in the discharge strand and in the load strand of the endless drive, which accelerations and delays lead to beating or knocking of the endless drive. Consequently the entire collective structural parts of the drive, especially the tooth belt connecting the crank shaft of the internal combustion engine with the one cam shaft are subjected to a high wear. The impacts, beating or knocking in the endless drive also is effective upon the tensioning shoes. The piston standing or existing under the pressure of the hydraulic medium is effective hereby like a stiff or rigid body, so that the tensioning shoes are strongly loaded and burdened by the impacting, beating and knocking of the endless drive and being subject to an increased wear.